Internal combustion engine with split pilot injection

ABSTRACT

An internal combustion engine includes a housing defining an internal cavity, an inner body sealingly moving within the internal cavity for defining at least one combustion chamber of variable volume, a pilot subchamber in communication with the at least one working chamber, an ignition element in communication with the pilot subchamber, a main injector communicating with the at least one combustion chamber, and a pilot injector having a tip in communication with the pilot subchamber. The tip of the pilot injector includes at least a first injection hole defining a first spray direction and a second injection hole defining a second spray direction different from the first spray direction. The first spray direction extends toward the communication between the pilot subchamber and the at least one working chamber. A method of performing combustion in an internal combustion engine is also discussed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No.15/153,277, filed May 12, 2016, the entire contents of which areincorporated by reference herein.

TECHNICAL FIELD

The application relates generally to internal combustion engines and,more particularly, to such engines including a pilot injection.

BACKGROUND OF THE ART

Some internal combustion engines include a pilot subchamber incommunication with the main combustion or working chamber(s), and inwhich a pilot quantity of fuel is injected and ignited. The ignited fuelfrom the pilot subchamber then creates a torch performing ignition inthe working chamber(s), in which a main quantity of fuel is injected.

SUMMARY

In one aspect, there is provided an internal combustion enginecomprising: a housing defining an internal cavity; an inner bodysealingly moving within the internal cavity for defining at least onecombustion chamber of variable volume; a pilot subchamber incommunication with the at least one working chamber; an ignition elementin communication with the pilot subchamber; a main injectorcommunicating with the at least one combustion chamber; and a pilotinjector having a tip in communication with the pilot subchamber, thetip of the pilot injector including at least a first injection holedefining a first spray direction and a second injection hole defining asecond spray direction different from the first spray direction, thefirst spray direction extending toward the communication between thepilot subchamber and the at least one working chamber.

In another aspect, there is provided an internal combustion enginecomprising: a housing defining an internal cavity; an inner bodysealingly moving within the internal cavity for defining at least onecombustion chamber of variable volume; a pilot subchamber incommunication with the at least one working chamber; an ignition elementin communication with the pilot subchamber; a main injector incommunication with the at least one combustion chamber; and a pilotinjector having a tip including at least first and second injectionholes in communication with the pilot subchamber, the pilot injectorhaving a central longitudinal axis aligned with the communicationbetween the pilot subchamber and the at least one working chamber, thelongitudinal axis intersecting the first injection hole, the secondinjection hole being spaced from the central longitudinal axis.

In a further aspect, there is provided a method of performing combustionin an internal combustion engine, the method comprising: simultaneouslyinjecting first and second sprays of a pilot quantity of fuel with apilot injector, the first spray being directed toward a communicationbetween the pilot subchamber and a working chamber of the internalcombustion engine, the second spray being directed away from the firstspray; igniting the fuel within the pilot subchamber; injecting a mainquantity of fuel in the working chamber with a main injector; andcirculating the ignited fuel from the pilot subchamber into the workingchamber to ignite the main quantity of fuel in the working chamber.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures in which:

FIG. 1 is a partial, schematic cross-sectional view of a rotary internalcombustion engine in accordance with a particular embodiment;

FIG. 2 is a schematic cross-sectional view of an insert of the engine ofFIG. 1;

FIG. 3 is a schematic cross-sectional view of an insert in accordancewith another embodiment;

FIG. 4 is a schematic cross-sectional view of an insert in accordancewith a further embodiment;

FIG. 5 is a schematic cross-sectional view of a rotary internalcombustion engine in accordance with another embodiment;

FIG. 6 is a schematic cross-sectional view of a rotary internalcombustion engine in accordance with another embodiment;

FIG. 7 is a schematic cross-sectional view of a rotary internalcombustion engine in accordance with another embodiment;

FIG. 8 is a schematic cross-sectional view of a rotary internalcombustion engine in accordance with another embodiment;

FIG. 9 is a partial, schematic cross-sectional view of a rotary internalcombustion engine including an insert in accordance with a furtherembodiment;

FIG. 10 is a partial, schematic top view of the rotary engine and insertof FIG. 9;

FIG. 11 is a partial, schematic top view of the rotary engine of FIG. 9with the insert removed, showing part of a rotor of the rotary enginethrough the insert opening;

FIG. 12 is a partial, schematic cross-sectional view of a rotaryinternal combustion engine in accordance with another embodiment;

FIG. 13 is a partial, schematic top view of the engine of FIG. 12; and

FIG. 14 is a schematic, tridimensional cross-sectional view of part ofthe rotary internal combustion engine of FIG. 9.

DETAILED DESCRIPTION

Referring to FIG. 1, a rotary intermittent internal combustion engine 10known as a Wankel engine is schematically and partially shown. In aparticular embodiment, the rotary engine 10 is used in a compound cycleengine system such as described in Lents et al.'s U.S. Pat. No.7,753,036 issued Jul. 13, 2010, or such as described in Julien et al.'sU.S. Pat. No. 7,775,044 issued Aug. 17, 2010, or such as described inThomassin et al.'s U.S. patent publication No. 2015/0275749 publishedOct. 1, 2015, or such as described in Bolduc et al.'s U.S. patentpublication No. 2015/0275756 published Oct. 1, 2015, the entire contentsof all of which are incorporated by reference herein. The compound cycleengine system may be used as a prime mover engine, such as on anaircraft or other vehicle, or in any other suitable application. In anyevent, in such a system, air is compressed by a compressor beforeentering the Wankel engine, and the engine drives one or more turbine(s)of the compound engine. In another embodiment, the rotary engine 10 isused without a turbocharger, with air at atmospheric pressure, and/orwithout compounding turbines.

The engine 10 comprises an outer body 12 having axially-spaced end walls14 with a peripheral wall 18 extending therebetween to form an internalcavity 20. The inner surface 19 of the peripheral wall 18 of the cavity20 has a profile defining two lobes, which is preferably an epitrochoid.

An inner body or rotor 24 is received within the cavity 20, with thegeometrical axis of the rotor 24 being offset from and parallel to theaxis of the outer body 12. The rotor 24 has axially spaced end faces 26adjacent to the outer body end walls 14, and a peripheral face 28extending therebetween. The peripheral face 28 defines threecircumferentially-spaced apex portions 30 (only one of which is shown),and a generally triangular profile with outwardly arched sides. The apexportions 30 are in sealing engagement with the inner surface ofperipheral wall 18 to form three rotating working chambers 32 (only twoof which are partially shown) between the inner rotor 24 and outer body12. A recess 38 is defined in the peripheral face 28 of the rotor 24between each pair of adjacent apex portions 30, to form part of thecorresponding chamber 32.

The working chambers 32 are sealed. Each rotor apex portion 30 has anapex seal 52 extending from one end face 26 to the other and protrudingradially from the peripheral face 28. Each apex seal 52 is biasedradially outwardly against the peripheral wall 18 through a respectivespring. An end seal 54 engages each end of each apex seal 52, and isbiased against the respective end wall 14 through a suitable spring.Each end face 26 of the rotor 24 has at least one arc-shaped face seal60 running from each apex portion 30 to each adjacent apex portion 30,adjacent to but inwardly of the rotor periphery throughout its length. Aspring urges each face seal 60 axially outwardly so that the face seal60 projects axially away from the adjacent rotor end face 26 intosealing engagement with the adjacent end wall 14 of the cavity. Eachface seal 60 is in sealing engagement with the end seal 54 adjacent eachend thereof.

Although not shown in the Figures, the rotor 24 is journaled on aneccentric portion of a shaft and includes a phasing gear co-axial withthe rotor axis, which is meshed with a fixed stator phasing gear securedto the outer body co-axially with the shaft. The shaft rotates the rotor24 and the meshed gears guide the rotor 24 to perform orbitalrevolutions within the internal cavity 20. The shaft rotates three timesfor each complete rotation of the rotor 24 as it moves around theinternal cavity 20. Oil seals are provided around the phasing gear toprevent leakage flow of lubricating oil radially outwardly thereofbetween the respective rotor end face 26 and outer body end wall 14.

At least one inlet port (not shown) is defined through one of the endwalls 14 or the peripheral wall 18 for admitting air (atmospheric orcompressed) into one of the working chambers 32, and at least oneexhaust port (not shown) is defined through one of the end walls 14 orthe peripheral wall 18 for discharge of the exhaust gases from theworking chambers 32. The inlet and exhaust ports are positioned relativeto each other and relative to the ignition member and fuel injectors(further described below) such that during each rotation of the rotor24, each chamber 32 moves around the cavity 20 with a variable volume toundergo the four phases of intake, compression, expansion and exhaust,these phases being similar to the strokes in a reciprocating-typeinternal combustion engine having a four-stroke cycle.

In a particular embodiment, these ports are arranged such that therotary engine 10 operates under the principle of the Miller or Atkinsoncycle, with its volumetric compression ratio lower than its volumetricexpansion ratio. In another embodiment, the ports are arranged such thatthe volumetric compression and expansion ratios are equal or similar toone another.

As described further below, a subchamber, which in the particularembodiment shown is a pilot subchamber 72, is defined in the outer body12, for pilot fuel injection and ignition. In this example, thesubchamber 72 is provided in an insert 34 received in a correspondinginsert opening 36 defined through the peripheral wall 18 of the outerbody 12 and in communication with the internal cavity 20, for pilot fuelinjection and ignition. The peripheral wall 18 also has a main injectorelongated hole 40 defined therethrough, in communication with theinternal cavity 20 and spaced apart from the insert 34. A main fuelinjector 42 is received and retained within this corresponding hole 40,with the tip 44 of the main injector 42 communicating with the cavity 20at a point spaced apart from the insert 34. The main injector 42 islocated rearwardly of the insert 34 with respect to the direction R ofthe rotor rotation and revolution, and is angled to direct fuelforwardly into each of the rotating chambers 32 sequentially with a tiphole pattern designed for an adequate spray.

Referring particularly to FIG. 2, in this example the insert includes anelongated body 46 extending across a thickness of the peripheral wall18, with an enlarged flange 48 at its outer end which is biased awayfrom a shoulder 50 defined in the peripheral wall 18, and against agasket (not shown) made of an appropriate type of heat resistantmaterial such as a silica based material. A washer 56, such as forexample a steel or titanium washer, and spring 58, such as for example awave spring or a Belleville spring, are provided between the flange 48and the shoulder 50 of the peripheral wall 18. The spring 58 biases thebody 46 against a cover 62 having a cross-section greater than that ofthe insert opening 36 and extending over an outer surface 64 of theperipheral wall 18. The cover 62 is connected to the peripheral wall 18,for example through brazing. Alternate types of connections can also beused, including but not limited to a connection through fasteners suchas bolts, to help facilitate replacement of the insert if necessary.

The insert body 46 has an inner surface 66 which is continuous with theinner surface 19 of the peripheral wall 18 to define the cavity 20. Theinsert opening 36 in the wall 18 defines a flange 68 extending in theinsert opening 36 adjacent the inner surface 19, and the inner end ofthe insert body 46 is complementarily shaped to engage this flange 68,with a gasket 70 being received therebetween.

In this example, the insert body 46 is made of a material having agreater heat resistance than that of the peripheral wall 18, which in aparticular embodiment is made of aluminium. In this particularembodiment, the insert body 46 is made of an appropriate type ofceramic.

The insert body 46 has a pilot subchamber 72 defined therein incommunication with the internal cavity 20. In the embodiment shown, thesubchamber 72 has a circular cross-section; alternate shapes are alsopossible. The subchamber 72 communicates with the cavity through atleast one opening 74 defined in the inner surface 66. The subchamber 72has a shape forming a reduced cross-section adjacent the opening 74,such that the opening 74 defines a restriction to the flow between thesubchamber 72 and the cavity 20. The opening 74 may have various shapesand/or be defined by a pattern of multiple holes. As can be seen in FIG.2, the opening 74 has an area smaller than the maximum cross-sectionalarea of the subchamber 72, which is defined spaced apart from theopening 74.

The peripheral wall 18 has a pilot injector elongated hole 76 definedtherethrough in proximity of the insert 34, extending at a non-zeroangle with respect to a surface of an outer wall of the insert 34 andwith respect to the longitudinal direction of the insert (which in theembodiment shown corresponds to the direction of the transverse axis Tof the outer body 12). The pilot injector hole 76 is in communicationwith the subchamber 72. A pilot fuel injector 78 is received andretained within the corresponding hole 76, with the tip 80 of the pilotinjector 78 being received in the subchamber 72. As can be seen in FIG.2, the insert body 46 has an injector opening defined therethroughproviding the communication between the pilot injector elongated hole 76and the subchamber 72, and the tip 80 of the pilot injector 78 isreceived in the subchamber 72 through this injector opening, with amajor part of the pilot injector 78 being received in the pilot injectorelongated hole 76 outside of the insert 34. The opening providing thecommunication between the pilot injector elongated hole 76 and thesubchamber 72 has an area smaller than the maximum cross-sectional areaof the subchamber 72.

The insert body 46 and cover 62 have an ignition element elongated hole82 defined therein extending along the direction of the transverse axisT of the outer body 12, also in communication with the subchamber 72. Ascan be seen in FIG. 2, the ignition element elongated hole 82 and thesubchamber 72 communicate through an opening having an area smaller thanthe maximum cross-sectional area of the subchamber 72. An ignitionelement or igniter 84 is received and retained within the correspondinghole 82, with the tip 86 of the ignition element 84 being received inthe subchamber 72. In the embodiment shown, the ignition element 84 is aglow plug. Alternate types of ignition elements 84 which may be usedinclude, but are not limited to, plasma ignition, laser ignition, sparkplug, microwave, etc. In a particular embodiment, the ignition element84 may be turned off when the walls of the subchamber 72 aresufficiently hot to ignite the fuel in the subchamber 72.

The pilot injector 78 and main injector 42 inject fuel, which in aparticular embodiment is heavy fuel e.g. diesel, kerosene (jet fuel),equivalent biofuel, etc. into the chambers 32. Alternately, the fuel maybe any other adequate type of fuel suitable for injection as described,including non-heavy fuel such as for example gasoline or liquid hydrogenfuel. In a particular embodiment, at least 0.5% and up to 20% of thefuel is injected through the pilot injector 78, and the remainder isinjected through the main injector 42. In another particular embodiment,at most 10% of the fuel is injected through the pilot injector 78. Inanother particular embodiment, at most 5% of the fuel is injectedthrough the pilot injector 78. The main injector 42 injects the fuelsuch that each rotating chamber 32 when in the combustion phase containsa mixture of air and fuel, which in a particular embodiment is a leanmixture.

Referring to FIG. 3, an insert 134 according to another embodiment isshown, engaged to the same outer body 12. The insert 134 extends acrossa thickness of the peripheral wall 18, and includes an inner bodyportion 146 and an outer body portion 162 which are attached together,for example through a high temperature braze joint 188. The outer bodyportion 162 has an enlarged flange 148 at its outer end which abuts theouter surface 64 of the peripheral wall 18 and is connected thereto, forexample through bolts with appropriate sealing such as a gasket or crushseal (not shown). Alternate types of connections can also be used,including but not limited to a brazed connection.

The inner body portion 146 has an inner surface 166 which is continuouswith the inner surface 19 of the peripheral wall 18 to define the cavity20. The inner end of the inner body portion 146 is complementarilyshaped to engage the flange 68 extending in the insert opening 36adjacent the inner surface 19, with a gasket 70 being receivedtherebetween.

In this particular embodiment, the body portions 146, 162 are made of anappropriate type of super alloy such as a Nickel based super alloy.

The subchamber configured as a pilot subchamber 72 is defined in theinsert 134 at the junction between the body portions 146, 162, with theinner body portion 146 defining the opening 74 for communication betweenthe subchamber 72 and the cavity 20. The outer body portion 162 has theignition element elongated hole 82 defined therein along the directionof the transverse axis T and in communication with the subchamber 72.The ignition element 84 is received and retained within thecorresponding hole 82, for example through threaded engagement. As inthe previous embodiment, the tip 86 of the ignition element 84 isreceived in the subchamber 72.

Referring to FIG. 4, an insert 234 according to another embodiment isshown. The insert 234 is received in a corresponding insert opening 236defined through the peripheral wall 18. The insert 234 includes an innerbody portion 246 and an outer body portion 262 which are attachedtogether, for example through a high temperature braze joint, with thesubchamber 72 being defined at the junction of the two portions 246,262. The inner body portion 246 defines the opening 74 for communicationbetween the subchamber 72 and the cavity 20.

The outer body portion 262 has the ignition element elongated hole 82defined therethrough in communication with the subchamber 72. The outerbody portion 262 includes an inner enlarged section 245 connected to theinner body portion 246 and defining the subchamber 72. The enlargedsection 245 extends substantially across the width of the insert opening236 around the subchamber 72, then tapers to a reduced width section 247extending therefrom. The reduced width section 247 has at its outer endan enlarged flange 248 which abuts a shoulder 250 defined in the outersurface 64 of the peripheral wall 18 around the insert opening 236. Anouter section 249, which in the embodiment shown has a widthintermediate that of the sections 245 and 247, extends outwardly fromthe flange 248. The flange is connected to the shoulder, for examplethrough bolts (not shown) with appropriate sealing such as a crush sealor a gasket (not shown) made of high temperature material, for example asilica based material or grafoil, between the flange 248 and shoulder250. Alternate types of connections can also be used.

The inner body portion 246 has an inner surface 266 which is continuouswith the inner surface 19 of the peripheral wall 18 to define the cavity20. The inner body portion 246 includes a groove defined therearoundnear the inner surface 266, in which an appropriate seal 251, forexample a silica based gasket tape, is received in contact with thewalls of the insert opening 236. In this embodiment, the walls of theinsert openings 236 are straight adjacent the inner surface 19, i.e.there is no flange adjacent the inner surface 19.

The volume of the pilot subchamber 72 in the insert 34, 134, 234 isselected to obtain a stoichiometric mixture around ignition within anacceptable delay, with some of the exhaust product from the previouscombustion cycle remaining in the subchamber 72. In a particularembodiment, the volume of the subchamber 72 is at least 0.5% and up to3.5% of the displacement volume, with the displacement volume beingdefined as the difference between the maximum and minimum volumes of onechamber 32. In another particular embodiment, the volume of thesubchamber 72 corresponds to from about 0.625% to about 1.25% of thedisplacement volume.

The volume of the pilot subchamber 72 may also be defined as a portionof the combustion volume, which is the sum of the minimum chamber volumeVmin (including the recess 38) and the volume of the subchamber V2itself. In a particular embodiment the subchamber 72 has a volumecorresponding to from 5% to 25% of the combustion volume, i.e. V2=5% to25% of (V2+Vmin). In another particular embodiment, the subchamber 72has a volume corresponding to from 10% to 12% of the combustion volume,i.e. V2=10% to 12% of (V2+Vmin).

The subchamber 72 may help create a stable and powerful ignition zone toignite the overall lean main combustion chamber 32 to create thestratified charge combustion. The subchamber 72 may improve combustionstability, particularly but not exclusively for a rotary engine whichoperates with heavy fuel below the self-ignition of fuel. The insert 34,134, 234 made of a heat resistant material may advantageously create ahot wall around the subchamber which may further help with ignitionstability.

The teachings herein are applicable to any suitable types ofintermittent internal combustion engines, including reciprocatingengines and many rotary engine types, and not just Wankel engines.Therefore, in another embodiment, the engine with subchamber the 72 maybe a non-Wankel engine. A “non-Wankel” engine, as used in thisdescription and the appended claims, means a rotary engine suitable foruse with the present invention, but excluding Wankel type engines.

In a particular embodiment, the rotary engine may be a single oreccentric type rotary engine in which the rotor rotates about a fixedcenter of rotation. For example, the rotary engine may be a sliding vaneengine, such as described in U.S. Pat. No. 5,524,587 issued Jun. 11,1996 or in U.S. Pat. No. 5,522,356 issued Jun. 4, 1996, the entirecontents of both of which are incorporated by reference herein.

Referring to FIG. 5, an example of a sliding vane engine 100 is shown.The engine 100 includes an outer body 112 defining an internal cavity 20receiving a rotor 124 having a number of vanes 125. The rotor 124includes an inner hub assembly 127 rotating about a first axis and anouter hub assembly 129 rotating about a second axis offset from thefirst axis, with the two hub assemblies 127, 129 being mechanicallylinked. The vanes 125 are pivotally connected to the inner hub assembly127 and are slidingly engaged through slots defined between adjacentsections of the outer hub assembly 129. The sections of the outer hubassembly 129 are thus sealingly engaged to the vanes 125 at differentdistances from the first axis of the inner hub assembly 127, defining aplurality of chambers 32 of variable volume within the cavity 20 aroundthe rotor 124.

In the embodiment shown, the engine 100 includes the subchamber 72described above, in this example defined in the insert 34 received in aninsert opening 36 of a peripheral wall 118 of the outer body 112. Theperipheral wall 118 also has a main injector elongated hole 40 definedtherethrough, in communication with the internal cavity 20 and spacedapart from the insert 34. The insert is biased against the cover 62retaining the insert 34 within the insert opening 36. The insert 34 ismade of a material having a greater heat resistance than that of theperipheral wall 118 and defines the pilot subchamber 72 in communicationwith the internal cavity 20 through at least one opening 74. Theperipheral wall 118 and/or the insert 34 has the pilot injectorelongated hole 76 and the ignition element elongated hole 82 definedtherethrough in communication with the subchamber 72. Other embodimentsmay be provided for the insert in the engine 100, including, but notlimited to, the other inserts 134, 234 described above.

In another particular embodiment, the rotary engine may be anoscillatory rotating engine, including two or more rotors rotating atdifferent angular velocities, causing the distance between portions ofthe rotors to vary and as such the chamber volume to change. Referringto FIG. 6, an example of such an engine is shown. The engine 200includes an inner rotor 224 and an outer body or rotor 212 rotating atdifferent angular velocities, the outer rotor 212 defining an internalcavity 20 in which the inner rotor 212 is received. Chambers 32 ofvariable volume are defined within the cavity 20 around the inner rotor224.

In the embodiment shown, the engine 200 includes the subchamber 72described above, in this example defined in the insert 34 received in aninsert opening 36 of a peripheral wall 218 of the outer body 212. Theperipheral wall 218 also has the main injector elongated hole 40 definedtherethrough spaced apart from the insert 34, and the peripheral wall218 and/or the insert 34 has the pilot injector elongated hole 76 andthe ignition element elongated hole 82 defined therethrough. Otherembodiments may be provided for the insert in the engine 200, including,but not limited to, the other inserts 134, 234 described above.

In another particular embodiment, the rotary engine is a planetaryrotating engine having a different geometry than that of the Wankelengine. Referring to FIG. 7, an example of such an engine is shown. Theengine 300 includes an outer body 312 forming an internal cavity 20 witha peripheral inner surface thereof having an epitrochoid profiledefining three lobes. The engine 300 also includes a rotor 324 with fourapex portions 330 in sealing engagement with the peripheral innersurface to form four rotating working chambers 32 of variable volumewithin the cavity 20 around the rotor 324. The rotor 324 is journaled onan eccentric portion of a shaft and performs orbital revolutions withinthe cavity 20.

In the embodiment shown, the engine 300 includes the subchamber 72described above, in this example defined in the insert 34 received in aninsert opening 36 of a peripheral wall 318 of the outer body 312. Theperipheral wall 318 also has the main injector elongated hole 40 definedtherethrough spaced apart from the insert 34, and the peripheral wall318 and/or the insert 34 has the pilot injector elongated hole 76 andthe ignition element elongated hole 82 defined therethrough. Otherembodiments may be provided for the insert in the engine 300, including,but not limited to, the other inserts 134, 234 described above.

The subchamber 72 may be provided integrally within the outer body 12,112, 212, 312 of the engine 10, 100, 200, 300, provided the outer body12, 112, 212, 312 is made of a material having adequate heat resistanceand such other properties required to provide a suitable outer body.Referring to FIG. 8, the Wankel engine 10 is shown with the subchamber72, pilot injector hole 76 and ignition element hole 82 integrallydefined in the outer body 12, more particularly in the peripheral wall18. In a particular embodiment, the outer body 12 is made of a materialhaving a heat resistance greater than that of aluminium. In a particularembodiment, the outer body 12 is made of an appropriate type of ceramicor of an appropriate type of super alloy, such as for example a Nickelbased super alloy. Though not shown, a wear insert may be provided inthe internal cavity 20 for contacting the rotor sliding surfaces. Theintegral subchamber may be applied to any of the rotary engineconfigurations contemplated by the present description.

Referring to FIG. 9, a rotary engine 400 and an insert 434 according toanother embodiment is shown. Although the engine 400 is depicted as aWankel engine, with an outer body including a peripheral wall 418extending between two axially spaced apart end walls 14 to define aninternal cavity 20 receiving a rotor 24, it is understood that theengine 400 may alternately be any other adequate type of intermittentinternal combustion engine, including, but not limited to, the rotaryengines described above.

The insert 434 is removably received in an insert opening 436 extendingacross a thickness of the peripheral wall 418 of the outer body of theengine 400. The insert 434 includes an elongated insert body 446, withan enlarged flange 448 at its outer end which abuts shoulders 464defined by the insert opening 436 having an enlarged cross-sectionadjacent its communication with the outer surface of the peripheral wall418. Alternately, the flange 448 can abut the outer surface of theperipheral wall 418. A seal 448A is disposed between the flange 448 andthe shoulders 464 to seal the insert opening 436. The seal 448A can be aC-seal or any other suitable seal. The insert opening 436 is located ator near top dead center, downstream of the main fuel injector 42communicating with the internal cavity 20 of the engine 400 and upstreamof a maximum temperature and pressure region of the internal cavity 20.The maximum pressure and temperature region is defined as a region ofthe chambers 32 just after top dead center. The fuel in the internalcavity 20 is ignited before top dead center (BTDC) and releases itsenergy such that maximum compression of the gas mixture is obtained justafter top dead center (ATDC) (i.e. just after the minimum volume for thechambers 32). In a particular embodiment, the maximum pressure obtainedin this region is in the order of 1500 psi.

The insert body 446 has an inner surface 466 which is continuous with aninner surface 19 of the peripheral wall 418 defining the internal cavity20. The insert opening 436 has a reduced cross-section adjacent theinner surface 19, the reduced cross-section being defined by a flange468 of the peripheral wall 418 surrounding and protruding into theinsert opening 436 adjacent the inner surface 19. The inner end of theinsert body 446 is complementarily shaped to engage this flange 468;optionally, a gasket may be received between the insert body 446 andflange 468, for example at 470. In the embodiment shown, the outersurface of the flange 468 abutting the insert body 446 is frusto-conicalsuch that a thickness of the flange 468 is progressively reduced towarda central axis of the insert opening 436; other configurations are alsopossible.

The insert body 446 has a subchamber configured as a pilot subchamber472 defined therein in communication with the internal cavity 20. In theembodiment shown, the subchamber 472 has a circular cross-section;alternate shapes are also possible. The subchamber 472 communicates withthe cavity 20 through at least one opening 474 defined in the innersurface 466.

In this embodiment, the peripheral wall 418 has a pilot injectorelongated hole 476 defined therethrough in proximity of the insert 434and communicating with the insert opening 436. The pilot injectorelongated hole 476 has a shape similar to the pilot injector elongatedhole 76 described above. The pilot injector hole 476 is in communicationwith the subchamber 472 through an injector opening 488A defined in theinsert body 446, and which has an area smaller than the maximumcross-sectional area of the subchamber 472. A pilot fuel injector 478 isreceived and retained within the corresponding hole 476. However, inthis embodiment, the pilot fuel injector 478 extends with its tip 480received in the pilot injector hole 476 without any part of the pilotfuel injector 478 protruding in the insert opening 436; the injectoropening 488A is thus free of the pilot fuel injector 478. The pilot fuelinjector 478 is clear from the subchamber 472 and the insert opening 436to allow removal of the insert 434 without the need to removing thepilot fuel injector 478.

Referring to FIGS. 10 and 11, a threaded hole 494 is provided (e.g.centrally disposed) in the flange 448 of the insert 434, configured toreceive and having a shape complementary to that of a threaded tool.Upon engagement with the threaded hole 494, the threaded tool mayfacilitate removal of the insert 434 from the insert opening 436 whenrequired, for example for inspection or maintenance.

In the embodiment shown, the insert 434 is removably retained in theinsert opening 436 by four threaded fasteners such as bolts 496 (FIG.10) engaging the flange 448 of the insert 434 and the peripheral wall418 through corresponding threaded holes 448B (FIG. 11) to secure theinsert 434 with respect to the peripheral wall 418. It is understoodthat other types of fasteners allowing for the insert to be removablyretained (e.g. retained such as to be removable without requiring tobreak, cut or damage the insert, wall or fastening mechanism) and/ordifferent numbers of fasteners can also be used (e.g. one or more).

Referring to FIG. 12, the peripheral wall 418 has at least one ignitionelement elongated hole 482 defined therein, angled with respect to thetransverse axis T of the outer body 12 and in communication with thesubchamber 472 and the insert opening 436. The ignition elementelongated hole 482 and the subchamber 472 communicate through an opening488B in the insert body 446 aligned with the hole 182 and having an areasmaller than the maximum cross-sectional area of the subchamber 472. Anignition element 484 is received and retained within the correspondingignition element elongated hole 482 in heat transfer communication withthe subchamber 472. In the embodiment shown, a tip 486 of the ignitionelement 484 is received in the subchamber 472. Alternately, the tip 486of the ignition element 484 can be outside of the subchamber 472,opening 488B and/or insert opening 436 (for example, so that no part ofthe ignition element 484 penetrates the insert opening 436), and theheat transfer communication may be performed with or without a fluidcommunication between the ignition element elongated hole 482 and thesubchamber 472 (for example, the opening 488B may be omitted).

Referring to FIG. 13, in a particular embodiment, two ignition elements484 are provided in communication with the subchamber 472. The ignitionelements 484 are provided in different planes, so that each ignitionelement 484 is extending along a respective axis 498, the axes 498intersecting. In a particular embodiment, the axes are disposed at a 30degrees angle from each other. Alternately, the number and/ororientation of the ignition elements 484 can differ.

As can be seen in FIGS. 9 and 12, a plurality of coolant passages 499are defined throughout the peripheral wall 418 (and although not shown,similar coolant passages may extend through the peripheral walls 18,118, 218, 318 described above), including, but not limited to, inproximity of the insert 434. The coolant passages 499 are in fluidcommunication with one another by being part of a cooling circuitrythrough which a liquid coolant (e.g. water) circulates in a closed loopwith a heat exchanger or any other element suitable to cool the usedcoolant for recirculation to the engine. The size and number of thecoolant passages 499 are selected such as to be able to maintain theperipheral wall 418 at temperatures below the applicable maximumthreshold for the material of the peripheral wall 418.

In the embodiment shown in FIGS. 12-13, the ignition elements 484 extendwithin the peripheral wall 418 along most of their length, which mayfacilitate cooling of the ignition elements 484 using the coolingcircuitry provided in the outer body through the peripheral wall 418.

In a particular embodiment, the presence of coolant passages 499 canimpede inspection, for example preventing the provision of a dedicatedinspection port, particularly for the hotter regions where more coolingis required and where the presence of such a port could disturb thecooling pattern. In a particular embodiment, the presence of the insert34, 134, 234, 434 allows for the insert opening 36, 236, 436 to be usedas an inspection port, taking advantage of this existing opening toperform visual inspection of the internal cavity 20 through a region ofthe peripheral wall which includes the cooling passages 499. Since theinsert 34, 134, 234, 434 is located adjacent the fuel injectors whichare typically readily accessible in use for maintenance purposes, in aparticular embodiment the insert 34, 134, 234, 434 is also readilyaccessible in use to be removed from the engine without the need to movethe engine. Prior methods of rotary engine inspection include inspectionthrough the inlet or outlet ports; the insert opening 36, 236, 436 iscloser to the high pressure and temperature region of the engine thanthe ports, and accordingly in a particular embodiment provides for abetter access to the portions of the internal cavity 20 which are mostsusceptible to damage. Prior methods of rotary engine inspection alsoinclude inspection through the hole left by removal of the ignitionelement; however, such inspection requires the use of inspection tools,for example a boroscope, since the hole is too small to be usable forvisual and/or manual inspection. In a particular embodiment, the insertopening 36, 236, 436 is advantageously sized to allow for visual and/ormanual inspection.

In a particular embodiment, inspection in the internal cavity 20 (i.e.of features of the outer body inside the internal cavity 20 and/or ofthe rotor 24 received therein) is performed in accordance with thefollowing. If the ignition element(s) 484 extend(s) within theperipheral wall 418 and protrude(s) into the insert opening 436, theignition element(s) 484 is/are disengaged from the insert 434. In anembodiment where the ignition element(s) is/are not engaged in theinsert 434, or where the ignition element(s) 84, is/are received in theinsert 34, 134, 234 without extending through the peripheral wall suchas to be removable together with the insert 34, 134, 234 in a same step,this step may accordingly be omitted.

Similarly, if a fuel injector extends within the peripheral wall andprotrudes into the insert opening, the fuel injector is disengaged fromthe insert. In an embodiment where the fuel injector is not engaged inthe insert, received in the insert without extending through theperipheral wall such as to be removable together with the insert in asame step, this step may accordingly be omitted.

The insert 34, 134, 234, 434 is then removed from the insert opening 36,236, 436 of the outer body, thereby providing access to the internalcavity 20 through the insert opening 36, 236, 436. To facilitate removalof the insert by a user, a threaded tool may be inserted into thethreaded hole 494 provided in the insert 434 (a similar threaded holemay be provided in any of the inserts described herein) and a force isthen applied on the threaded tool, for example a pulling force.

Once the insert 34, 134, 234, 434 is removed, the internal cavity 20 isinspected through the insert opening 36, 236, 436. The inspection can bedone visually and/or manually. The inspection can include, but is notlimited to, any one or any combination of inspecting the condition ofthe apex seals 52, inspecting the condition and/or operation of thespring(s) biasing the apex seals 52, inspecting the condition of acoating applied to the inner surface 19 of the peripheral wall 18, 118,218, 318, 418 and/or to the inner surface 491 of the end walls 14,inspecting the condition of the rotor 24 itself (e.g. presence ofcracks), verifying if liquid coolant and/or oil is present in thechambers 32, inspecting the fuel injector (e.g. its tip), particularlyfor the fuel injector communicating with the chamber but having aconfiguration allowing the insert to be removed without prior removal ofthe fuel injector, etc. Inspection of the condition of the coating caninclude inspection to detect one or more of pitting, erosion,delamination and cracks in the coating surface.

Following the results of inspection, appropriate maintenance and/orrepair operations may be performed. Non-limiting examples of suchoperations include, with a prior step of disassembly of the engine inwhole or in part when required:

-   -   When the condition of the apex seals 52 and/or of the spring(s)        biasing the apex seals 52 is determined to be inadequate        following the inspection, replacing damaged ones of the apex        seals 52 and the springs;    -   When the condition of the coating applied to the inner surface        19 of the peripheral wall 18, 118, 218, 318, 418 and/or to the        inner surface 491 of the end walls 14 is determined to be        inadequate following the inspection, recoating the parts where        the defects were detected, optionally stripping the existing        coating before the recoating operation;    -   When the condition of the rotor 24 itself is determined to be        inadequate following the inspection, performing required repairs        to the rotor (e.g. weld repair or replacement) or replacing the        rotor as a whole;    -   When the presence of liquid coolant in the chambers 32 is        detected, replacing a broken or defective seal of the cooling        (e.g. o-ring), and/or inspecting the outer body to find a crack        responsible for the leak and repairing the crack or replacing        the damaged part;    -   When the presence of oil in the chambers 32 is detected,        replacing a broken or defective oil seal, or repair or        replacement of the element responsible for the leak, with        optional pressure testing to determine which element is        responsible if the failure is not apparent;    -   When damage to the fuel injector (e.g. pilot fuel injector) is        detected, replacing or repairing the fuel injector.

In a particular embodiment, a boroscope is optionally inserted throughthe insert opening 436, as a follow-up to a preliminary visualinspection, to further inspect the internal cavity 20. The use of theboroscope can advantageously provide a wider access to the internalcavity 20.

Referring back to FIGS. 10 and 11, the width 490 of the internal cavityis defined as the distance between the inner surfaces 491 of the endwalls 14 along a direction parallel to a rotational axis RA of the rotor24. In a particular embodiment and referring to FIG. 11, the width 492of the insert opening 436, i.e. of its cross-section, definedperpendicularly to the thickness of the peripheral wall 418 (e.g.parallel to the rotational axis RA), is sufficiently large throughoutthe thickness of the peripheral wall 418 to be able to perform anunaided (i.e. without inspection instruments or tools) visual inspectionof the internal cavity 20 through the insert opening 436; the minimalwidth is thus sized to correspond to, at least, a minimum dimensionrequired for visual inspection, based on the size of the human eye.

In the embodiment of FIG. 9, the minimum width 492′ of the insertopening 436 is a minimum diameter, since the insert opening 436 has acircular cross-section, and is located adjacent the inner surface 19 ofthe peripheral wall 418, i.e. at the radially innermost point of theinsert opening 436. In a particular embodiment, the minimum width 492′is at least equal to ⅓ of the width 490 of the internal cavity 20. In aparticular embodiment, the minimum width 492′ of the insert opening 436is between ⅓ and ½ of the width 490 of the internal cavity 20. Forexample, in a particular embodiment, the minimum width or diameter 492′of the insert opening 436 is at least 0.75 inch; in a particularembodiment, such a minimum width is sufficient to allow for visualinspection through the insert opening. In particular embodiments, theminimum width 492′ of the insert opening 436 may correspond to any oneof the following: at least 0.8 inch; at least 0.85 inch; at least 0.9inch; at least 0.93 inch; about 0.93 inch; at least 1 inch. It isunderstood that the particular dimensions provided herein are alsoapplicable to the insert openings 36, 236 of the other embodimentsdiscussed.

The ability to perform visual inspection is highly desirable, and in aparticular embodiment allows for reduction of the costs and/or timeassociated with preliminary inspections, as opposed to engineconfigurations which require instruments and/or disassembly of thehousing to be inspected; a larger insert opening 36, 236, 436 providesbetter exposure of the internal cavity 20 for visual inspection.

It is understood that the removable insert 34, 134, 234, 434 allowinginspection of the internal cavity 20 through the insert opening 36, 236,436 is not limited to an insert defining a pilot subchamber for pilotignition. For example, in particular embodiments, the removable insert34, 134, 234, 434 allowing inspection of the internal cavity 20 throughthe insert opening 36, 236, 436 is an insert defining other types ofsubchambers, such as for example a pre-chamber for combustion, where thewhole volume of fuel is injected for ignition—i.e. where the maininjector is in communication with the pre-chamber in the insert. Otherconfigurations are also possible.

Referring to FIG. 9, in a particular embodiment, the tip 480 of thepilot injector 478, which is in direct communication with the pilotsubchamber 472, includes at least two injection holes 480A, 480Bconfigured to inject fuel in two sprays 481A, 481B extending alongdifferent directions. Each injection hole 481A, 481B is in fluidcommunication with the injection mechanism of the pilot injector 478, sothat the pilot quantity of fuel is injected through the injection holes481A, 481B simultaneously, with a relative size of the injection holes481A, 481B determining the proportion of fuel injected in eachdirection. As can be also seen in FIG. 14, each spray 481A, 481B isillustrated by a cone, showing an exemplary fuel dispersal patternfollowing injection of fuel through the respective injection hole 480A,480B. In a particular embodiment, the direction of the spray 481A, 481Bis defined by the central axis 483A, 483B of the dispersal pattern, i.e.the central axis of the cone.

It can be seen that the spray direction defined by the first injectionhole 480A extends toward the communication between the pilot subchamber472 and each working chamber 32. For example, in the embodiment shown,the axis 483A of the first spray 481A extends through the opening 474 inthe insert 434 which defines the communication between the pilotsubchamber 472 and each working chamber 32 of the internal cavity 20.

In the embodiment shown, the spray direction defined by the secondinjection hole 480B extends away from the communication between thepilot subchamber 472 and the working chamber 32. For example, the axis483B of the second spray 481B intersects the wall of the pilotsubchamber 472 away from the opening 474 in the insert 434 which definesthe communication between the pilot subchamber 472 and the workingchamber 32. The second spray direction 483B is shown as extending towardthe ignition elements 484. Although in the embodiment shown the secondspray 481B does not directly intersect the ignition elements 484, it isunderstood that alternately the second spray 481B could directlyintersect the ignition element(s) 484 and/or their communication withthe pilot subchamber 472. It is also understood that the second spray481B could be directed to any location in the pilot subchamber 472 notcorresponding to the direction of the communication between the pilotsubchamber 472 and the working chamber 32; for example, the second spray481B could be directed so that at a given engine speed, the interactionbetween the second spray 481B and an air swirl present in the pilotsubchamber 472 (determined, for example, by computational fluid dynamics(CFD) analysis) provides for the fuel and air to be sufficiently mixedin the vicinity of the ignition element(s) 484.

In the embodiment shown and as can be seen in FIG. 9, the centrallongitudinal axis L of the pilot injector 478 extends through theopening 474 in the insert 434 which defines the communication betweenthe pilot subchamber 472 and the working chamber 32. The centrallongitudinal axis L intersects the first injection hole 480A, and in theembodiment shown corresponds to the axis 483A of the direction of thefirst spray 481A. The second injection hole 480B is spaced from thecentral longitudinal axis L of the pilot injector 478. It is howeverunderstood that other orientations for the pilot injector 478 are alsopossible.

In a particular embodiment, the first injection hole 480A which directsfuel toward the communication with the working chamber 32 has a greatercross-sectional area than that of the second injection hole 480B whichdirects fuel away from the communication with the working chamber 32,e.g., toward the ignition element(s) 484. In a particular embodiment,this allows for a major part of the pilot fuel to be directed toward thecommunication with the working chamber 32 while providing for some fuelflow toward the ignition element(s) 484, away from the communicationwith the working chamber 32. For example, in a particular embodiment,the pilot injector performs a total injection of 40 cc of fuel, with thefirst and second holes 480A, 480B being relatively sized so that 15 cc(37.5%) of the pilot fuel is directed toward the ignition element(s) 484and the remaining 25 cc (62.5%) of the pilot fuel is directed toward thecommunication with the working chamber 32. It is however understood thatthe particular fuel quantities are provided as an example only, and thatproportions can vary, including, but not limited to, for engines havingdifferent compression ratios and/or subchamber sizes. For example, inanother embodiment, 20% of the pilot fuel is directed toward theignition element(s) 484 and the remaining 80% of the pilot fuel isdirected toward the communication with the working chamber 32. Otherproportions are also possible.

Moreover, although two injection holes 480A, 480B are shown, it isunderstood that two or more injection holes could be directed toward thecommunication with the working chamber 32 and/or two or more injectionholes could be directed away from the communication with the workingchamber 32, for example toward the ignition element(s) 484.

Although described with reference to the engine 400 shown in FIGS. 9-11and 14, it is understood that the pilot injection with split sprays maybe used with the pilot injector 78, 478 of any of the engines 10, 100,200, 300 of FIGS. 1-8 and 12-13, and in any other suitable internalcombustion engine configuration, including, but not limited to,non-rotary internal combustion engines such as reciprocating engineswhere the inner body sealingly moving within the internal cavity is areciprocating piston defining a single working chamber of variablevolume in the internal cavity.

In use, in a particular embodiment, performing combustion in an internalcombustion engine (any of the engines shown, a reciprocating engine,etc.) includes simultaneously injecting first and second sprays 481A,481B of a pilot quantity of fuel with the pilot injector 78, 478, wherethe first spray 481A is directed toward the communication 74, 474between the pilot subchamber 72, 472 and the working chamber 32, and thesecond spray 481B is directed away from the first spray 481A. The fuelis ignited within the pilot subchamber 72, 472. The main quantity offuel is injected in the working chamber 32 with the main injector 42,and the ignited fuel is circulated from the pilot subchamber 72, 472into the working chamber 32 to ignite the main quantity of fuel in theworking chamber 32.

In a particular embodiment, the first spray 481A is directed along thecentral longitudinal axis L of the pilot injector 78, 478, and/or thesecond spray 481B is directed toward the ignition element(s) 84, 484.For example, when two spaced apart ignition elements 484 are provided,the second spray 481B may be directed between the two ignition elements484.

It is understood that the fuel may be ignited without the help of theignition elements 84, 484; for example, once the engine is started, thewalls of the pilot subchamber 72, 472 may be sufficiently hot to ignitethe fuel, so that the ignition element(s) 84, 484 may be turned off.

As mentioned above, in a particular embodiment the first spray 481Aincludes a greater volume of fuel than that of the second spray 481B.

In a particular embodiment, the split pilot injection defined by the twodifferent sprays 481A, 481B from the pilot injector 78, 478 allows todirect part of the pilot injection towards the ignition element(s) 84,484 to ensure proper ignition in the subchamber 72, 472, while directinganother part of the pilot injection through the pilot subchamber 72, 472and into the working chamber 32 to ensure that the main fuel charge isignited as a result of the combustion in the pilot subchamber 72, 472.In a particular embodiment, the split pilot injection provides forimproved ignition and combustion efficiency as well as easier enginestarts and relight than a corresponding pilot injection with a singlespray.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention(s)disclosed. For example, the mechanical arrangements of the enginesdescribed above are merely examples of many possible configurationswhich are suitable for use with the present invention(s). Any suitableinjector configuration and arrangement may be used. Hence, modificationswhich fall within the scope of the present invention will be apparent tothose skilled in the art, in light of a review of this disclosure, andsuch modifications are intended to fall within the appended claims.

The invention claimed is:
 1. An internal combustion engine comprising: ahousing defining an internal cavity; an inner body sealingly movingwithin the internal cavity for defining at least one working chamber ofvariable volume; a pilot subchamber in communication with the at leastone working chamber; an ignition element in communication with the pilotsubchamber; a main injector communicating with the at least one workingchamber; and a pilot injector having a tip in communication with thepilot subchamber, the tip of the pilot injector including at least onefirst injection hole and at least one second injection hole, the atleast one first injection hole configured to form a first spray having afirst spray direction, the at least one second injection hole configuredto form a second spray having a second spray direction different fromthe first spray direction, the first spray direction extending toward acommunication the pilot subchamber and the at least one working chamber,the at least one first injection hole and the at least one secondinjection hole being configured such that first spray includes a greatervolume of fuel than the second spray.
 2. The internal combustion engineas defined in claim 1, wherein the second spray direction extends awayfrom the communication between the pilot subchamber and the at least oneworking chamber.
 3. The internal combustion engine as defined in claim1, wherein the second spray direction extends toward the ignitionelement.
 4. The internal combustion engine as defined in claim 1,wherein the pilot subchamber is defined in an insert received in a wallof the housing, the pilot subchamber communicating with the at least oneworking chamber through an opening defined in the insert, and whereinthe first spray has a central axis extending through the opening.
 5. Theinternal combustion engine as defined in claim 4, wherein the secondspray has a central axis intersecting a wall of the pilot subchamber ata location spaced apart from the opening.
 6. The internal combustionengine as defined in claim 1, wherein the first spray direction extendsalong a central longitudinal axis of the pilot injector.
 7. The internalcombustion engine as defined in claim 1, wherein the at least one firstinjection hole has a greater cross-sectional area than that of the atleast one second injection hole.
 8. The internal combustion engine asdefined in claim 1, wherein the internal combustion engine is a rotaryengine, the inner body is a rotor having three apex portions mounted foreccentric revolutions within the internal cavity, the internal cavityhaving an epitrochoid shape with two lobes.
 9. The internal combustionengine as defined in claim 1, wherein the at least one first injectionhole and the at least one second injection hole are relatively sizedsuch the first spray includes at least 62.5% of a pilot quantity of fuelinjected by the pilot injector.
 10. An internal combustion enginecomprising: a housing defining an internal cavity; an inner bodysealingly moving within the internal cavity for defining at least oneworking chamber of variable volume; a pilot subchamber in communicationwith the at least one working chamber; an ignition element incommunication with the pilot subchamber; a main injector incommunication with the at least one working chamber; and a pilotinjector having a tip including at least first and second injectionholes in communication with the pilot subchamber, the first injectionhole configured to form a first spray having a first spray direction,the pilot injector having a central longitudinal axis aligned with acommunication between the pilot subchamber and the at least one workingchamber, the central longitudinal axis intersecting the first injectionhole and the first spray direction corresponding to the centrallongitudinal axis, the second injection hole being spaced from thecentral longitudinal axis.
 11. The internal combustion engine as definedin claim 10, wherein the second spray direction has a central axisintersecting a wall of the pilot subchamber at a location spaced apartfrom the communication between the pilot subchamber and the at least oneworking chamber.
 12. The internal combustion engine as defined in claim11, wherein the spray direction of the second injection hole extendstoward the ignition element.
 13. The internal combustion engine asdefined in claim 10, wherein the pilot subchamber is defined in aninsert received in a wall of the housing, the pilot subchambercommunicating with the at least one working chamber through an openingdefined in the insert, and wherein the central longitudinal axis extendsthrough the opening.
 14. The internal combustion engine as defined inclaim 10, wherein the first injection hole has a greater cross-sectionalarea than that of the second injection hole such that first sprayincludes a greater volume of fuel than the second spray.
 15. Theinternal combustion engine as defined in claim 10, wherein the internalcombustion engine is a rotary engine, the inner body is a rotor havingthree apex portions mounted for eccentric revolutions within theinternal cavity, the internal cavity having an epitrochoid shape withtwo lobes.
 16. A method of performing combustion in an internalcombustion engine, the method comprising: simultaneously injecting firstand second sprays of a pilot quantity of fuel in a pilot subchamber witha pilot injector, the first spray being directed toward a communicationbetween the pilot subchamber and a working chamber of the internalcombustion engine, the second spray being directed away from the firstspray; igniting the fuel within the pilot subchamber; injecting a mainquantity of fuel in the working chamber with a main injector; andcirculating the ignited fuel from the pilot subchamber into the workingchamber to ignite the main quantity of fuel in the working chamber. 17.The method as defined in claim 16, wherein igniting the fuel isperformed with an ignition element, and wherein the second spray isdirected toward the ignition element.
 18. The method as defined in claim16, wherein igniting the fuel is performed with two spaced apartignition elements, and wherein the second spray is directed between thetwo ignition elements.
 19. The method as defined in claim 16, whereinthe first spray includes a greater volume of fuel than the second spray.20. The method as defined in claim 16, wherein the first spray isdirected along a central longitudinal axis of the pilot injector. 21.The method as defined in claim 16, wherein the internal combustionengine is a rotary engine, the inner body is a rotor having three apexportions mounted for eccentric revolutions within the internal cavity,the internal cavity having an epitrochoid shape with two lobes.